20 Most Recent 2008 GMC Sierra 1500 2WD Questions & Answers

DTC P0121: Throttle Position (TP) Sensor 1 Performance Circuit/System Description The engine control module (ECM) uses the following information to calculate an expected airflow rate: ?€¢ The throttle position (TP)

?€¢ The barometric pressure (BARO)

?€¢ The manifold absolute pressure (MAP)

?€¢ The intake air temperature (IAT)

?€¢ The engine RPM

P0121 The predicted air flow and the predicted MAP combined are outside a calibrated range for more than 3 seconds. Circuit/System Testing

1. Inspect for the following conditions:
?€¢ Vacuum hoses for splits, kinks, and proper connections as shown on Vehicle Emission Control Information label

?€¢ Inspect thoroughly for any type of leak or restriction

?€¢ Air leaks at throttle body mounting area and intake manifold sealing surfaces

?€¢ Throttle body for dirt, debris, and coking--Refer to Throttle Body Cleaning.

2. Allow the engine to reach operating temperature. Observe the MAP Sensor Voltage parameter with a scan tool. Voltage should be more than 0.8 volt and less than 4 volts.
?‡' If more than 4 volts or less than 0.8 volt, refer to DTC P0106.
3. Idle the engine. Observe the MAP Sensor kPa parameter with a scan tool. Increase the engine speed slowly and then back to idle. The MAP sensor kPa should change smoothly and gradually as engine speed is increased and returned to idle.
?‡' If the MAP sensor kPa does not change, refer to DTC P0106.
4. Take a snapshot of the engine data list while performing the actions listed below. The mass air flow (MAF) sensor g/s should change smoothly and gradually as the engine speed is increased and is returned to idle.
?€¢ Idle the engine.

?€¢ Increase the engine speed slowly to 3,000 RPM, then back to idle.

?€¢ Exit from the snapshot and review the data.

?€¢ Observe the Mass Air Flow (MAF) Sensor parameter frame by frame with a scan tool. The MAF sensor g/s should change smoothly and gradually as the engine speed is increased and is returned to idle.

?‡' If the MAF sensor g/s does not change smoothly and gradually as the engine speed is increased and is returned to idle, refer to DTC P0101 or P1101.

5. Inspect the throttle body for the following conditions:

?€¢ Loose or damaged throttle blade

?€¢ Broken throttle shaft

?€¢ Any throttle body damage

?‡' If any of these conditions exist, replace the throttle body assembly.

18436572

Get a new mechanic. Or a technician would be better. If it.s not the wiring then its probably the motor.

I think I would try a new ignition switch or at least unplug the switch after the engine is running and see if it stops running. When you initiate a start, a series of relays turn on in the powerbox. If the ignition relay is melted inside itself, it will not break connection. You can research and get diagrams, videos, and photos on the Web. Just be specific and enter the year, make, and model and ask for a wiring diagram or fusebox or powerbox for that truck. Then chose from the results. You should be able to identify the correct relay from the diagrams. Relays are not terribly expensive.

the split ring in steering column is a ground to horn relay if wire touch ground or pad is compress horn will be active hope it helps

No you will not.

p0449evap emissions system control valve vent/solenoid circuit malfunction p0455evap emissions system control leak detected [gross leak] usually u check ur gas cap and vent lines for a problem because it is usually the problem but check the wiring and connections to the purge valve also check for leak around the purge valve

Where i s oil drain plug?GMC 2008 Sierra